yeah and you could just drill some things for the spikes to go into. Your only using 4 bucks. spray paint em if you want a diff color. and you could use some of that steel putty stuff and make the tops flat too.
Superballs..... get the one inch superballs from .25 cent gumball machine outside of your local supermarket or Walmart. Use the ones that have a bit of roughness to them. If they are smooth or have sparklies in them, they are not as good.
Then you can buy from Home Depot or a hardware store - or even Walmart, maybe! - plastic one inch "feet" or floor protectors that are usually used to prevent chair legs or other furniture from scratching the floor. They fit right over the end of the chair leg and are about $2.49 a package. Or you can go to the asile where they have screws and bolts and threaded steel bars and pick up the same thing for $.18 cents each.
Superballs fit inside these feet.
Sand down the smooth bottom surface of the feet to hinder it's sliding capabilities...